A moratorium on hydraulic fracturing has been under effect in South Africa since April, 2011.

On Friday 25 March, environmental activist Lewis Pugh delivered a passionate call to action at a public lecture in Cape Town. He implored South Africans to stand up for our rights – particularly the right to water, and the right to a healthy environment – and take on corporate bullies like Shell. If you care about the Karoo, if you care about our country, keep reading...

Ladies and gentlemen, that is what is at stake here today: our children's future. And that of our children's children.

There may be gas beneath our ground in the Karoo. But are we prepared to destroy our environment for five to ten years worth of fossil fuel and further damage our climate? Yes, people will be employed – but for a short while. And when the drilling is over, and Shell have packed their bags and disappeared, then what? Who will be there to clean up? And what jobs will our children be able to eke out?

Now Shell will tell you that their intentions are honourable. That fracking in the Karoo will not damage our environment. That they will not contaminate our precious water. That they will bring jobs to South Africa. That gas is clean and green. And that they will help secure our energy supplies. When I hear this, I have one burning question. Why should we trust them? Africa is to Shell what the Gulf of Mexico is to BP.

Shell, you have a shocking record here in Africa. Just look at your operations in Nigeria. You have spilt more than 9 million barrels of crude oil into the Niger Delta. That's twice the amount of oil that BP spilt into the Gulf of Mexico. You were found guilty of bribing Nigerian officials, and to make the case go away in America, you paid an admission of guilt fine of $48 million. And to top it all, you stand accused of being complicit in the execution of Nigeria's leading environmental campaigner, Ken Saro-Wira, and eight other activists. If you were innocent, why did you pay $15.5 million to the widows and children to settle the case out of court?

Shell, the path you want us to take us down is not sustainable. I have visited the Arctic for seven summers in a row. I have seen the tundra thawing. I have seen the retreating glaciers. I have seen the melting sea ice. And I have seen the impact of global warming from the Himalayas all the way down to the low-lying Maldive Islands. Wherever I go, I see it.

Now is the time for change. We cannot drill our way out of the energy crisis. The era of fossil fuels is over. We must invest in renewable energy. And we must not delay.

Shell, we look to the north of our continent and we see how people got tired of political tyranny. We have watched as despots, who have ruled ruthlessly year after year, have been toppled in a matter of weeks. We too are tired. Tired of corporate tyranny. Tired of your short-term, unsustainable practices. We watched as Dr Ian Player, a game ranger from Natal, and his friends, took on Rio Tinto (one of the biggest mining companies in the world) and won. And we watched as young activists from across Europe, brought you down to your knees, when you tried to dump an enormous oil rig into the North Sea.

Shell, we do not want our Karoo to become another Niger Delta. Do not underestimate us. Goliath can be brought down. We are proud of what we have achieved in this young democracy, and we are not about to let your company come in and destroy it.

So let this be a call to arms to everyone across South Africa, who is sitting in the shadow of Goliath: stand up and demand these fundamental human rights promised to you by our Constitution. Use your voices – tweet, blog, petition, rally the weight of your neighbours and of people in power. Let us speak out from every hilltop. Let us not go quietly into this bleak future.

Let me end off by saying this: you have lit a fire in our bellies, which no man or woman can extinguish. And if we need to, we will take this fight all the way from your petrol pumps to the very highest court in this land. We will take this fight from the farms and towns of the Karoo to the streets of London and Amsterdam. And we will take this fight to every one of your shareholders. And I have no doubt, that in the end, good will triumph over evil. DM

Lewis Pugh is a lawyer and environmental activist. He belongs to the Treasure the Karoo Action Group.